1. Field
Exemplary embodiments of the present disclosure relate to an image forming apparatus, and more specifically to a liquid ejection head that ejects droplets of liquid, a liquid-droplet ejection device including the liquid ejection head, and an image forming apparatus including the liquid ejection head.
2. Description of the Background
Image forming apparatuses are used as printers, facsimile machines, copiers, plotters, or multi-functional peripherals having two or more of the foregoing capabilities. As one type of image forming apparatus employing a liquid-ejection recording method, an inkjet recording apparatus is known that uses a recording head formed with a liquid ejection head (liquid-droplet ejection head) for ejecting droplets of ink.
Such image forming apparatuses employing the liquid-ejection recording method eject droplets of ink or other liquid from the recording head onto a recording medium to form a desired image (hereinafter “image formation” is used as a synonym for “image recording” and “image printing”). Such liquid-ejection-type image forming apparatuses fall into two main types: a serial-type image forming apparatus that forms an image by ejecting droplets from the recording head while moving the recording head in a main scan direction, and a line-head-type image forming apparatus that forms an image by ejecting droplets from a linear-shaped recording head held stationary in the image forming apparatus.
Such a liquid ejection head supplies ink from an ink tank to a plurality of separate chambers (also referred to as pressure chambers or separate supply channels) via a common chamber and selectively applies pressure to ink in the separate chambers to eject liquid droplets from nozzles. Consequently, if at this time impurities, contaminated materials, or other foreign materials are mixed in with the ink supplied, these separate chambers may be blocked, causing clogging of the nozzles and ejection failure.
Hence, conventionally, a filter is disposed at a supply port of the common chamber. It is known that the closer the filter is located to the nozzles or the separate chambers, the more effectively the filter removes foreign materials. In another conventional technique, such a filter unit is formed in a diaphragm member between the common chamber and individual liquid-supply passages that supply liquid to the separate chambers. Further, in order to maintain good liquid supply to the separate chambers, communicating portions are formed in the partition walls between the individual liquid-supply passages at a side opposite a side facing the diaphragm member, thus causing the individual liquid-supply passages to be communicated with each other.
However, as described above, when the communicating portions are formed at the side facing the diaphragm member, the partition walls between the individual liquid-supply passages face the filter. As a result, a portion of the filter is shielded by the partition walls to narrow the filtering area, which is substantially the same as when the filter is provided for each of the separate chambers. Consequently, accumulation of even a slight amount of foreign materials may increase the proportion of a non-filtering area relative to the whole area of the filter, causing loss of pressure and a reduction in performance.